Transformer wiring problem - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 1st December 2005, 11:44 AM   #1
sumacSK is offline sumacSK  Slovakia
diyAudio Member
 
Join Date: Jun 2004
Location: Prague
Send a message via ICQ to sumacSK
Default Transformer wiring problem

Hi all,

I'm in process of building LM3875 stereo amp based on brian's rev.3 board. I've ordered a transformer (200VA, 2*19V). It has arrived today, but it is not transformer with dual secondaried (as I thought it will be) but it looks exactly like this: http://ezk.cz/images/tor16.jpg . If I understand it correctly, it is center-tapped transformer. So now, I'm little unsure how to wire it to rectifier board. Can anybody explain it to me?

Thanks Martin
  Reply With Quote
Old 1st December 2005, 12:02 PM   #2
Wynand is offline Wynand  South Africa
diyAudio Member
 
Wynand's Avatar
 
Join Date: Mar 2005
Location: Cape Town
Put the Two black wires on mains ( put fuse in-line)
Then measure the ac voltage on the other side.

Then (as I can see) the red wires are your secondaries with the center one being ground. The center one is just the windings that are already connected.

The center tap is the wire that always gives a lower voltage.

Just wait for someone to confirm this... or be VERY VERY carefull.

I dont want to kill you with bad advice.
  Reply With Quote
Old 1st December 2005, 12:53 PM   #3
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Apparently the red wire with the 4 leads is the center tap, the red ones with the 2 wires are the top and bottom leads (which are interchangeable of course). The black ones are the mains leads.
I am not familiar with your particular board, but the center tap should go to ground (no surprise here!) while the other ones should go to each end of the double-phase rectifier. If you post a schematic of your rectifier setup we can exactly tell you where they should go.

Jan Didden
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W S Maugham
Check out Linear Audio!
  Reply With Quote
Old 1st December 2005, 02:00 PM   #4
sumacSK is offline sumacSK  Slovakia
diyAudio Member
 
Join Date: Jun 2004
Location: Prague
Send a message via ICQ to sumacSK
Hi,

here is schematic of rectifier board, but it is using transformer with dual secondaries: http://www.audiosector.com/lm4780%20psu.pdf Here is users guide this gainclone: http://chipamp.com/nigc_kit-users_guide.pdf . There is also shown how to wite center tapped transformer, so if I uderstand it correctly, those 2 red wires (top and bottom leads) goes to AC1N and AC1H, AC2 stays unused, and center tap goes to PG+ and PG- . Also only 4 diodes should be used.

Is that right?

Thanks Martin
  Reply With Quote
Old 2nd December 2005, 12:36 PM   #5
kec is offline kec  United States
diyAudio Member
 
kec's Avatar
 
Join Date: Mar 2001
Location: California
sumacSK,

I ran into the same situation as you did. On my monoblocks I have the center tap going to PG- (black wire) and the other 2 to AC1N (red wire) and AC1H (blue wire). You can see how I did mine in this image: http://img.photobucket.com/albums/v521/kecline/GC12.jpg

But since you're doing a stereo version GC it may be slightly different.

-Ken
  Reply With Quote
Old 2nd December 2005, 01:47 PM   #6
sumacSK is offline sumacSK  Slovakia
diyAudio Member
 
Join Date: Jun 2004
Location: Prague
Send a message via ICQ to sumacSK
Hi Ken,

Thanks for your response, it seems that you solved my problem... I hope it will work...

Thanks Martin
  Reply With Quote
Old 2nd December 2005, 06:07 PM   #7
diyAudio Member
 
mrlots2do's Avatar
 
Join Date: May 2004
Location: Philadelpia
Quote:
Originally posted by sumacSK
here is schematic of rectifier board, but it is using transformer with dual secondaries: http://www.audiosector.com/lm4780%20psu.pdf Here is users guide this gainclone: http://chipamp.com/nigc_kit-users_guide.pdf .
Ok.... I'm not trolling, just some observations from viewing the above schematics. And Yes I heard wiring ct trans up as I'm about to suggest will let the smoke out.

Here goes:
Wiring sec 1 to AC2H, center tap to AC2N and AC1H, sec 2 to AC1N. Why can't the center tap of trans be wired to AC2N and AC1H? I see V+ to PG+ as plus rail and PG- to V- as neg rail.

To go a step farther, couldn't PG+ and PG- be spliced together. I say this because I enlarged the pdf file looking at the pcb's and I don't see a short. Can someone please tell me were the short occurs?

To go a step farther, page 15 of the manual shows PG+ and PG- are common to the amp board. This narrows the possible short to the rectifier layout.
  Reply With Quote
Old 2nd December 2005, 06:10 PM   #8
diyAudio Member
 
mrlots2do's Avatar
 
Join Date: May 2004
Location: Philadelpia
Quote:
Originally posted by mrlots2do

Wiring sec 1 to AC2H, center tap to AC2N and AC1H, sec 2 to AC1N. Why can't the center tap of trans be wired to AC2N and AC1H? I see V+ to PG+ as plus rail and PG- to V- as neg rail.
I forgot to mention, above is using 8 diodes.
  Reply With Quote
Old 2nd December 2005, 06:52 PM   #9
sumacSK is offline sumacSK  Slovakia
diyAudio Member
 
Join Date: Jun 2004
Location: Prague
Send a message via ICQ to sumacSK
Hi mrlots2do,

Thanks for your response, but I cutted off those 4 diodes, just while before your post...

So, I have to go the 4 diode way... Will it work good also for stereo???

Thanks Martin
  Reply With Quote
Old 2nd December 2005, 07:08 PM   #10
diyAudio Member
 
mrlots2do's Avatar
 
Join Date: May 2004
Location: Philadelpia
Quote:
Originally posted by sumacSK
So, I have to go the 4 diode way... Will it work good also for stereo???
The rectifier board is designed for two amp board supplies. I don't believe using the 4 diode schematic changes how many amp supplies it can handle.

My 2 cents
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Transformer wiring roadie Solid State 2 23rd June 2009 03:33 PM
Transformer wiring problem ebenai Chip Amps 3 7th May 2007 06:56 PM
Push Pull Output Transformer wiring problem cyl Tubes / Valves 8 25th April 2007 02:23 AM
Transformer wiring zlast Solid State 2 18th May 2006 10:31 PM
Wiring of a transformer AudioFreak Parts 20 20th January 2002 02:40 PM


New To Site? Need Help?

All times are GMT. The time now is 09:49 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2